NATIONAL BUREAU OF STANDARDS REPORT NBS PROJECT N B S REPORT
8550 - 30- 85454 June 20, 1960 6705
MEASURED PERFORMANCE
OF AN HI? I
LOG-PERIODIC ANTENNA
P. P. Viezbicke
U. S. DEPARTMENT O F COMMERCE NATIONAL BUREAU OF STANDARDS
BOULDER LABORATORIES Boulder, Colorado
IMPORTANT NOTICE
NATIONAL BUREAU OF STANDARDS REPORTS are usually preliminary or progress accounting docu- ments intended for use within the Government. Before material i n the reports is formally published it is subjected to additional evaluation and review. For th is reason, the publication, reprinting, reproduc- tion, or open-literature listing of this Report, either in whole or in part, i s not authorized unless per- mission is obtained i n writing from the Office of the Director, National Bureau of Standards, Washington 25, D. C. Such permission i s not needed, however, by the Government agency for which the Report has been specifically prepared if that agency wishes to reproduce additional copies for i t s own use.
. 1
FOR E W OR D
This report presents the results of measure-
ments made on an HF log-periodic antenna located
in Northern New York State.
The measurements were made by the Antenna
Research Section of the Radio Systems Division,
National Bureau of Standards, Boulder Laboratories,
at the request of the Ground Electronics Engineering
Installation Agency in co-operation with RADC. The
work was carried out as project 85454, USAF Opera-
tional Antenna Meas ur em ent s.
CONTENTS
MEASURED PERFORMANCE OF A N HF LOG-PERIODIC ANTENNA
P. P. Viezbicke
Abstract
The performance of an operational log-periodic antenna was tested at frequencies of 12, 18, 24, 36, 48, and 60 Mc/s. A t each frequency, values of impedance, gains, and radiation patterns were measured. In addition, radiation patterns were measured at 18 Mc/s with the axis of the antenna rotated to different bearing angles. This measurement was designed to estimate the influence of terrain and adjacent structures on the pattern response of the t e s t antenna.
Values of voltage standing-wave ratio measured less than 1. 32:l at the different frequencies of operation. the midfrequency range showed higher gains and narrower beam- widths in contrast to measurements at the lower and higher frequency l imits of operation. Gains, slightly in excess of 6 decibels - relative to a dipole - and 66-degree-wide horizontally polarized beamwidths were measured from 18 to 48 Mc/s , as contrasted with 4 .5 decibels and approximately 75-degree-wide beamwidths a t the 12 and 60 MC/S frequencies of operation.
Measurements in
The influence of adjacent structures and terrain had dis- brting effects on the radiation patterns, resulting in reduced gain in the forward direction.
The performance of the antenna, in general, conformed to the data available from the manufacturer. However, observed gains and beamwidth measurements were not constant over the full frequency range.
- 2 -
1. INTRODUCTION
The purpose of this report is to present and evaluate the char-
acteristics of an HF operational log-periodic antenna, with respect
to impedance, gain, beamwidth and front-to-back ratio over a 5-to-1
frequency range.
tested over the period from November 9, 1959 to December 11, 1959.
The antenna, located in upstate New York, was
2. ANTENNA AND SITE
The log-periodic antenna, which exhibits relatively constant
characteristics that vary periodically a s the logarithm of the frequency
over an extremely wide band of frequencies, was f i rs t introduced by
R. H. DuHamel and D. E. Isbell.
cal aspects underlying the broadband characteristics, a limited dis-
cussion was included concerning the mechanics of the radiation pro-
perties of the antenna.
1 Although they present the theoreti-
In a more recent paper, however, R. L. Bell, C. T. Elfving,
and R. E. Franks present the theory of operation, substantiated by
measurements, describing the radiation properties of a type of log-
2
periodic antenna similar to that tested.
supports a TEM transmission wave which launches the far-field
radiation wave.
consisting of 5 elements within the antenna and centered around the
h/Z-long resonant element. Due to the direction, magnitude, and
phase relationship of the current and electric field distribution on
the elements within this region, a radiation field i s enhanced and
propagated in the reverse direction of the transmission-line wave.
The extremely wide bandwidth operation i s due to the selected antenna
design and geometry, whereby the electrical characteristics vary
periodically with the logarithm of the frequency.
They show that the antenna
The TEM wave terminates in an active region
- 3-
According to the available manufacturer ' s data, the antenna
tested provides a substantially uniform impedance characteristic, a
gain of approximately 6 decibels relative to a dipole, and a hori-
zontally polarized half-power beamwidth of 65 degrees over a
frequency bandwidth from 11.1 to 60 Mc/s.
The antenna consists of an arrangement of 13 tapered
transverse elements mounted to two 41-foot-long steel booms.
These elements a r e oriented to form an angle of 37 degrees.
a r r a y is located at a height of'75.5 feet above ground, and is
mounted to a single rotatable structure, as shown in Figure 1.
Construction details of one plane of the antenna a r e presented in
Figure 2.
The
The nominal 150-ohm antenna impedance is matched to 50
ohms by employing tapered sections of coaxial line located within
the lower boom section of the array.
vertical shaft comprises the 50-ohm feed line, and connects the
antenna to a rotating 3-1/8-inch coaxial joint located at the base of
the array.
The rotatable, motor-driven,
Because of i ts extreme broadband characteristic, the antenna
is adaptable to communication systems wher e operational frequencies
require repeated changing without the necessity of additional
structures or arrays.
Figure 3 i s a topographic view of the operational test site.
It shows the location of the different antenna a r rays , towers, and
buildings in the vicinity of the antenna tested.
-4 -
3 . METHODS OF MEASUREMENT
At each test frequency, impedance, gains, and radiation
patterns were measured, using commercially available test
equipment.
The input impedance to the antenna was measured remotely
through a 300-foot length of RG-9 coaxial cable.
line-length corrections in each case, the impedance a t the coaxial
input connection to the antenna was determined.
By introducing
The gain and radiation patterns were measured with the log-
periodic antenna used as a receiving antenna, matched to 50 ohms
for each test.
to the receiver-recording equipment located in a nearby van. An
equal length of cable was connected and matched to the reference
dipole antenna, located at the same height a s , and approximately
500 feet to one side of, the tes t antenna.
measured for each antenna and found to be within 0.1 to 0 . 2 decibels.
These were omitted in calculating the results.
A 300-foot-long coaxial cable connected the antenna
Cable losses were
When measuring the radiation pattern and gain of the
antenna, it was oriented to a bearing angle of 100 degrees east of
magnetic north.
overlooked terrain clear of objectionable reflecting obstacles.
Supplementing these 100-degree bearing tests, additional radiation
patterns were measured at bearing angles of 160, 280, and 340
degrees.
and were designed to determine the influence of the nearby ar rays ,
towers, and buildings on the performance of the test antenna.
In this direction, the main beam of the antenna
These tests were carried out at a frequency of 18-11 Mc/s
z
-5 -
Radiation patterns w e r e measured by recording the signal
from a crystal- controlled battery-powered tar get transmitter, and
a trailing antenna mounted aboard an aircraft.
360-degree circles at a range of from one to two miles from the
si te, at angles of departure ranging from 2 to 45 degrees.
flight around the test site, the aircraft was tracked optically by an
observer.
the roof of the van.
azimuth and elevation angles , w a s transmitted by syncro- generator 8
t o the automatic antenna pattern-r ecording equipment located inside
the van.
The airplane flew in
In its
The telescope, turntable and controls were mounted to
The direction to the aircraft, in terms of
Although the transmitted output power w a s maintained at a
constant level throughout a day's tests, the field-intensity recordings
had to be corrected for varying aircraft ranges from the site.
the process of conducting each test, the aircraft height and elevation
angle were continuously noted and recorded.
a i rcraf t observed the reading on a calibrated altimeter and periodi-
cally communicated the aircraft height. F r o m these data, corrections
up to 3 decibels in field intensity were made to compensate for
variations in range, using the inver se-distance- squared relationship.
In
The operator aboard the
In some instances, the aircraft flew to within one mile of the
As a result, parallax up to 3 degrees existed between the t e s t site.
location of the test antenna and the azimuthal-observation van.
maintain uniformity in measurements on all tests, parallax cor-
rections were incorporated in arriving at the final results.
T o
. ..
- 6 -
Antenna gain was measured by comparing the maximum
response of the test antenna to the maximum response of the dipole.
The dipole was periodically substituted for the test antenna while
the aircraft was in the direction of the main beam. The difference
i n the two corrected field-intensity responses revealed the gain of
the log-periodic antenna relative to the dipole.
The results of the measurements are presented in the form
of curves and radiation pattern contours, at each frequency of
operation.
conducted at 18.11 Mc/s, are presented in polar form only.
The results of the different bearing-angle pattern t e s t a ,
The measured pattern reeponaea are within a two-degree
azimuthal accuracy and the measured gains within one-decibel
accuracy.
4. RESULTS
The performance characteristics of the antenna, relative
to impedance, gain, and radiation pattern response, are herewith
presented.
While values of impedance were measured with the antenna
fixed in height, and influenced for the most part only by the ground
below, the gain and pattern measurements w e r e conducted under
conditions of varying parameters.
ments was subject to uncontrollable reflections caused by irregulari-
ties in the terrain and obstacles in the vicinity of the antenna at
different angles of departure and azimuth. The results presented,
therefore, characterize the antenna performance at this particular
site and location.
The latter phase of the measure-
-7-
Measured values of impedance (VSWR) a t the different
Figure 5 frequencies of operation are presented in Figure 4.
presents values of gain relative to a dipole over a similar fre-
quency range. It should be noted that the curves in each of the
figures could have deviated from those shown if measurements
had been conducted at smaller increments within the frequency
range.
that the values vary with frequency as indicated. .
However, for the purpose of presentation, it is assumed
Normalized vertical, azimuthal, and contour radiation
pattern responses at the different frequencies of operation are
presented in Figures 6 through 26.
The vertical pattern response curves presented in Figures
6, 9, 15, 18, 21 and 24 show the variation in field intensity at
angles of departure from approximately 2 to 45 degrees.
the antenna is at a fixed height of 75.5 feet above ground, the
electrical height varies with frequency from 1. Oh at 12 M c / s to
4.55), at 60 Mc/s.
increased from approximately two at 12 M c / s to seven at 60 M c / s
over the range of departure angles.
with respect to the maximum response of the dipole.
given in decibels, i s the maximum response of the antenna in
each case, a s indicated. For comparison purposes, predicted
vertical pattern responses, based on an H-plane beamwidth of 90
degrees, a r e presented with the measured responses.
Because
Consequently, the number of lobe maxima
The curves are normalized
The gain,
- 8-
Figures 7, 10, 16, 19, 22, and 25 present normalized
azimuthal response patternswithin the 3-decibel level of maximum
radiation at the different frequencies of operation.
ments were conducted with the axis of the antenna directed to the
100-degree azimuth.
radiation patterns a t 18. 11 Mc/s, with the axis of the antenna
directed to 160-, 280-, and 340-degree azimuths, respectively.
To show the effects of neighboring obstacles, the patterns are
plotted as an overlay on a topograpic view of the site.
These measure-
Figures 13 through 15 present the polar
Complete and detailed pattern characteristics at the different
operating frequencies a r e presented by the normalized contour
patterns shown in Figures 8, 11, 17, 20, 23, and 26.
intensity, structure, and occurrence of major - and minor -lobe
radiation over 360 degrees in azimuth and angles of departure from
2 to 45 degrees. The field-intensity contour points and lines a r e
presented at zero (maximum radiation), at half-power level, and
at subsequent 5-decibel levels, down to -30 decibels.
They represent
Characteristics vs. frequency
Horizontal ha l f - power beamwidth
Frequency Gain (db) Impedance VSWR (degrees) 12.975 4.5 39L-6 1. 32 75 18.110 6.4 56/12 I. 26 67 23.86 6.1 4 5 7 5 1. 16 66 36.04 6.3 53;i-j 1 . 1 3 66 47.7 5.7 53/-5 1.13 68 59.75 4.7 48/-5 1.08 73 -
Fr ont - to - back ratio
14 19 15 18 17 13
(db)
- 9-
5. DISCUSSION OF ANTENNA CHARACTERISTICS
5.1. Impedance and Gain
Measured values of impedance over the 5-to-1 frequency
range a r e presented in Figure 4.
with the available published data and a r e within a 2-to-1 VSWR at
the different frequencies tested.
entire range, with a maximum of 1. 32:l occurring at 12.975 Mc/s
and a minimum of 1.08:l at 59.75 Mc/s.
These values compare favorably
The response is uniform over the
Measured values of gain conformed to the published data in
the midfrequency range, but measured somewhat less at the low and
high frequency limits of operation.
gain of 6.4 decibels was measured at 18.11 M c / s and remained sub-
stantially constant throughout the range to 47.7 Mc/s.
and 59.75 Mc/s, however, the gain depreciates to 4.5 and 4.7
decibels respectively, or approximately 2 decibels less than that
measured at 18.11 Mc/s.
As shown in Figure 5, a maximum
A t 12.975
5.2. ’ Radiation Patterns a t 12.975 MC/S
The performance of the antenna, operating at a frequency of
12.975 Mc/s, i s characterized by the vertical, azimuthal, and
radiation pattern contours presented in Figures 6 through 8. The
shape of the vertical radiation pattern and the relative position of
the lobes (Figure 6) conformed to that which w a s calculated, except
that the second-lobe maximum was reduced in gain.
of departure from 35 to 45 degrees, the gain i s expected to be
A t angles
reduced by as much a s 6 decibels.
-PO-
The azimuthal radiation pattern presented in Figure 7 shows
irregularities, with a reduction of gain up to 2 decibels within the
blf-power beamwidth.
presence of the discone and large steerable a r r a y in front and to the
right side of the test antenna.
degrees is slightly greater than given in the published data, with
radiation to the rear irregular and approximately 14 decibels down
from that in the forward direction.
5.3. Radiation Patterns at 18.11 Mc/s
These deformations a r e probably due to the
The half-power beamwidth of 75
Optimum performance of the antenna was measured at an
operating frequency of 18.11 M c / s.
maximum gain, but the response patterns were uniform in the forward
direction with minimized side and rear radiation.
Not only did the antenna yield
Within the range of departure angles, maximum radiation
occurred at 8 and 30 degrees.
the preceding frequency of operation, the gain at the second lobe
Analogous to the results measured at
maximum was reduced by approximately 5 decibels. It is believed
that, at these lower frequencies, the reduction in gain at higher
angles of departure is due to siting and to the limited, smooth
terrain of the first Fresnel zone a rea in front of the antenna.
The azimuthal response pattern presented in Figure 10 was
uniform over a wide range in the forward direction.
discontinuities occurred at azimuths of 25 and 160 degrees, and a r e
believed to be due to the presence of the nearby discone and
steerable arrays.
and the front-to-back ratio measured 19 decibels.
Slight
The half-power beamwidth measured 67 degrees,
-11-
Supplementing the 1 00-de gr ee- bearing tests , radiation
patterns were measured with the axis of the antenna directed to
azimuths of 160, 280, and 340 degrees.
a r rays , buildings and obstructions on the shape of the pattern w e r e
determined and a r e represented by the curves given in Figures 12
through 14.
The effects of nearby
The largest deformation in the shape of the pattern occurred
Due to the deleterious effects at an antenna bearing of 160 degrees.
of the large steerable array, the gain of the tes t antenna w a s
reduced by 10 decibels in the forward direction, and prominent, ir-
regular radiation occurred to the rear .
radiation was only 12 decibels down from that in the forward direction.
Figure 13 represents the radiation pattern of the antenna
For the most part, r ea r
with its axis bearing to 280 degrees. Although undesirable
radiation occurred to the r ea r , that in the fo rward direction w a s
relatively uniform, with a slight asymmetry to one side. The gain
measured 1.5 decibels below the maximum, and the average front-
to-back ratio measur ed approximately 16 decibels.
Figure 14 presents the radiation pattern of the antenna bearing
at 340 degrees.
toward a large steerable a r r a y located approximately 1200 feet from
the test antenna. Even at this distance, impeding effects were
observed on the performance of the log-periodic antenna. These
effects account for the deterioration of the pattern in the forward
direction, and for reduced gain.
the right is believed due to scattering of energy by the steel microwave
towers and guy lines located in the foreground.
i n this case measured 14 decibels.
In this direction, the axis of the antenna pointed
The slight skewing of the beam to
Front-to-back ratio
I
- 1 2 -
It should be noted that the radiation patterns measured at
the 160-, 280-, and 340-degree azimuths were recorded at an
average angle of departure of 8.5 degrees, while that a t the 100-degree-
bearing angle w a s recorded at 6 .5 degrees. Even though a 2-degree
difference exists in departure angles between the tests, each may be
considered as the representative maximum response of the antenna.
(See Figure 9.)
5.4. Radiation Patterns at 23.86 Mc/s
A t this frequency of operation, considerable deviation in
the position and the shape of the vertical pattern lobe structure
existed between the predicted and measured responses. As r e -
presented by the curves in Figure 15, the first- and second-lobe
maxima occurred at angles of departure approximately 4 degrees
less than predicted.
The discrepancy in the shape and position of the first- and
second-lobe maxima is believed to be due to the effects of the sloping
first Fresnel zone a rea in front of the antenna and the scattering of
energy from the discone antenna located in the left foreground of the
test antenna. These deleterious effects on the shape of the pattern
were prominent up to 30 degrees, but did not seem to influence the
performance of the antenna at the higher angles.
Minor-lobe radiation to the side and rear w a s enhanced, as
indicated by the azimutRa1 response presented in Figure 16.
The radiation pattern showed irregularities up to 2 decibels
Radiation to the right, rear and left w a s in the forward direction.
from 12 to 15 decibels below the maximum. These undesirable
-13-
radiations w e r e caused by the presence of the nearby steerable array,
discone and microwave towers.
the pattern - at one point slightly in excess of 3 decibels - the half-
power beamwidth measured 66 degrees.
Discounting the deformations in
5.5. Radiation Patterns a t 36.04 Mc/s
Except for a slight deviation in the shape of the first-lobe
maximum, the measured radiation pattern in the vertical plane,
presented in Figure 18, compared favorably wi th that which w a s
calculated. At the different angles of departure, the lobe maximum
occurred within 2 degrees of the predicted, with the magnitude of
gain deteriorating to less than 2 decibels at the higher angles of
departure.
The azimuthal pattern, measured at an angle of departure
of 2.5 degrees, given in Figure 19, i s relatively uniform in the
forward direction, with no protruding lobes to the side and rear .
The half-power beamwidth measured 66 degrees. For the most
part , back radiation was below the 18-decibel level - except for a
single 13-decibel down spike occurring at 275 degrees.
5.6. Radiation Patterns at 47.7 MC/S
The radiation patterns measured at this frequency of operation
The vertical pattern response, agreed favorably with those predicted.
presented in Figure 21, shows the lobe maxima occurring within
one degree of that predicted.
a s the angle of departure increased.
within 2 decibels over the entire range.
It was displaced only slightly in position
The gain, however, remained
- 14-
Figure 22 presents the azimuthal pattern response a t the
second-lobe maximum a t an angle of departure oi I I degrees.
half-power beamwidth measured 68 degrees with deformation8
slightly in excess of 3 decibels - occurring at azimuths of 73 and
135 degrees.
lesser degree than at the lower frequencies of operation.
presence of the microwave towers showed no appreciable effects
on the pattern response.
Tile
The steerable a r rays influenced the pattern to a
The
Front-to-back ratio measured 17 decibels.
5.7. Radiation Patterns a t 59.75 Mc/s
The vertical pattern response, presented in Figure 24,
compared favorably with that predicted at low angles of departure.
However, at 25 degrees and higher, the gain of the antenna w a s
slightly reduced. Aside from this, the pattern responses w e r e
uniform and the maxima occurred within 2 degrees of the predicted
radiation patterns over the entire range.
The nearby steerable arrays, trees, and sloping terrain
influenced the shape of the pattern (Figure 25), and enhanced
undesirable radiation to the side and rear.
Analogous to results measured at the lowest frequency of
operation, the half-power beamwidth measured 73 degrees and the
front-to-back ratio measured 13 decibels. Both the larger beam-
widths and the higher secondary-lobe levels account for the lower
values of gain than that measured in the midfrequency range of
operation.
-15-
6 . CONCLUSIONS
In the frequency range, from 18. P 1 to 47.7 Mc/ s , the gain
of the antenna measured 6 decibels relative to a-half-wave dipole
located at the same height above ground.
however, the gain measured approximately 2.0 decibels less than
anticipated.
A t 12.975 and 59.75 Mc/s,
The half-power beamwidth measured 66 degrees in the 18.12
to 4 7 . 7 Mc/s frequency range and increased to 73 degrees at 12.975
and 59.75 Mc/s .
Front-to-rear radiation decreased from approximately 18
decibels in the midfrequencies to 13 decibels at the lowest and
highest frequencies of operation.
The effects of terrain and the presence of nearby obstacles
in the vicinity of the test antenna distorted the radiation pattern of
the antenna and reduced the gain for certain orientations of the
antenna e
The voltage standing-wave ratio measured less than 1:32 to
P over the entire frequency range of operation.
7. ACKNOWLEDGMENTS
Appreciation is extended to J. E. Chukoski and R. J. Heim for
their contribution in making the measurements and scaling the
recordings.
8. REFERENCES
1. R. €3. DuHamell and D. E. Psbell, Broadband logarithmically
periodic antenna structures, IRE Convention Record, Pa r t I.
1957, pp 119-128.
-16-
2. R . L. Bell, C. T. Elfving and R . E. Franks, Near-field
measurements on a logarithmically periodic antenna, Tech.
Memo. No. EDL - MZ31, December 21, 1959, Sylvania
Electric Products, Inc. , Electronic Defense Laboratory.
Figo 1: PICTORIAL V f E W OF ‘TB LOG-PERIODIC ANTENNA
/
Fig, 2 : CONSTRUCTION DETAILS OF ONE PLANE OF THE ANTENNA
ANTENNA
Fig. 3 : TOPOGRAPHIC VIEW OF THl3 OPEZUTIONAZ TEST SITE
2.0 t]
1.01
I I I I I
40 50 60 IO 20 30 0 0
FREQUENCY,MC
Fig. 41 MEASTlRED VALUES OF VSWR AT 1333 DIF€QXEEC FREQUENCIES OF OPEXLATION
7.0
6.0
5.0
4.( W
W J 0
a 4
0
W
c 4 J w
0
I- 3.1 2
a
E " 2. 4
I
I I 1 I I
I I 10 20 30
I I I
0' 0
FREOUENCY, MC
Fig. 5: MEASURED VALUES OF GAIN AT 'TIE DIFFEKWT FREQUENCIES OF OPE33ATIoN
45
4 0
35
30
u) w W
W w a
n - 2 f W a 3 I-
U
W
a n
n
LL 2 ( 0
w -I W z U
I !
I1
I I I I
I I /
/
I I I I I I -10 - 5 0 - 25 - 20 - I 5
N O R M A L I Z E D R E S P O N S E L E V E L , d b
NORMALIZl3D VERTICAL RADIATION PATTERN AT 12.975 Mc/s
Fig. 6: Electrical height of antenna, 1,OA Gain relative to a dipole, 4,5 db
Me as m e d - - - - Calculated
I I \
Fig, 7: Angle of departure, 12.5 degrees Half-power beamwidth, 75 degrees Gain r e l a t i v e -to a dipole, 4,5 db Front-to-rear radiat ion, 14 db
45
40
35
30
U J W W
W W
a
0 25
a
a
.. W
x c
2 W 0
L L 0 2( W -1 W z U
I
I
\ \
\ \
\ \ \ \ I
I /
/ /
/ /’
I I
1 - 25 - 20 -15 I I I I
-10 - 5 0 _ _ NORMALIZED RESPONSE LEVEL, db
NORMALIZED VERTICAL RADIATION PATTERN AT 18.110 M c / s
Fig. 9: Electrical height of antenna, 1 . 3 8 ~ - Measured Gain relative to a dipole, 6.4 db - - - calculated
I \ \
NORMALIZED AZIMUTHAL RADIATION PATTERN AT 18.110 Mc/s
Fig, 10: Angle of departure, 6 degrees Half -power beamwidth, 67 degrees Gain r e l a t i v e t o a dipole, 6.4 db Front-to-rear radiat ion, 19 db
NORMALIZED AZlNJTHAL RADIATION PATTERN AT 18,110 Mc/s
Fig. 12: Axis of main beam bearing t o 160 degrees Angle of departure, 8,5 degrees Front-to-rear radiation, 12 db
NORMALIZED AZIMUTHAL RADIATION PATTERN AT 18.110 MC/S
Fig. 13: Axis of main beam beasing to 280 degrees Angle of departure, 8,5 degrees Front-ta-rear radiation, 11 db
1200
NO3M!4LIZED AZIMUTHAL RADIATION PAT- AT 18.110 Mc/s
Fig. 14: Axis of main beam bearing t o 340 degrees Angle of departure, 8,5 degrees Front-to-rear radiation, 14 db
45
40
35
30
v) W w W w a
a 25
a
a
- W
3 e U Q w 0
L L O 2c W 2 W z U
I!
I(
/ /
'2 1 I I I 1
-20 -15 -10 - 5 0 I -25 NORMALIZED RESPONSE LEVEL, db
N O R M A L I W VERTICAL RADIATION PATTERN AT 23,860 Mc/s
Fig. 15: Electrical height of antenna, 1.821, Measured Gain relative t o a dipole, 6.1 db - - - - Calculated
NORMALIZED AZ- RADIATION PATTERN AT 23,860 Mc/s
Fig. 16: Angle of departure, 6,o degrees Half-power beaawidth, 66 degrees Gain r e l a t i v e t o a dipole, 6.1 db Front-to -rear radiat ion, 15 db
! 40
30
UJ w W
(3 w a
0 25 wi a =l c 9: 4
w 0
n
2 0 w -J (3 z U
IS
I(
\ \
I I I I I - 5 0 -10
NORMALIZED RESPONSE LEVEL, db -I 5 0 - 25 - 20
NORMALIZED VERTICAL RADIATION PATTERN AT 36.040 Mc/s
Fig. 18: E l e c t r i c a l height of astenna, 2.74A Measured
Gain r e l a t i v e t o a dipole, 6,3 db - - - - Calculated
\
I 2000 1900 1800
NORMALIZED AZIMUTHKG RADIATION PATTERN AT 36.040 MC/S
Fig, 19: Angle of departure, 2,5 degrees Half-power beamwidth, 66 degrees Gain r e l a t ive t o a dipole, 6.3 db
\
\ 45
40
3 5
30
u) w w W w a
0 25
a ..
w 2 + a U a. w a LL 0 20 w J W z U
15
IC
f
I I I I I -10 -5 0 - 25 - 2 0 - I5 -30
NORMALIZED RESPONSE LEVEL, db
NORMALIZED VERTICAL WIIATION PATTERN AT 47.700 MC/S
F ig , 21: E l e c t r i c a l height of antenna, 3.64h Measured Gain r e l a t i v e t o a dipole, 5.7 db - - - -Calculated
NORNALIZED AZIMLTTHAL RADIATION PATTERN AT 47.700 Mc/s
Fig, 22: Angle of departure, 11 degrees (2nd lobe ma,) Half-power beamwidth, 69 degrees Gain r e l a t i v e t o a dipole, 5.7 db Front -to -rear radiat ion, 17 db
45
40
35
30
rn w w W w a
2 5 - w a a I- a U n W n IL 0 20 w -1 (3 =? 4
15
IO
5
a - I - 25 - 20 - I 5 -10 - 5 0 NORMAL1 ZED RESPONSE LEVEL, db
N0RMPJ;IZED VERTICAL RADLkTION PATTERN A T 59.750 Mc/s
Me as ur e d Fig, 24: E l e c t r i c a l height of antenna, 4,55h Gain relative to a dipole, 4,7 db - - - - Calculated
, -
! ! I
NORMALIZED AZIMUTm RADIATION PATTERN AT 59.750 Mc/s
Fig, 25: Angle of departure, 8 degrees (2nd lobe max.) H a l f - p w e r beamwidth, 73 degrees Gain r e l a t i v e t o a dipole, 4.7 db Front-to-rear radiat ion, 13 db
